[sdiy] Introducing Milton: New sequencer in town

[Peter Grenader]

Kids,

I have completed a working prototype of my VCS (voltage controlled
sequencer) which operationally harkens back to the Buchla 200's monsters.

It's working name being Milton, it has 16 steps by up to 15 banks (I'll get
to that in a second) and is fully voltage controllable.  By this I mean
there is an analog voltage input which overrides the counting sequence and
allows the operator to assign it to any step the incoming voltage dictates.
This input is quantized into 16 partitions and assings the output step
accordingly.  You want random? Put in a S+H sampling noise.  You want
pendulum? Put in triangle wave.  Backwards?  A ramp wave.  This plus a
billion different patterns your incoming voltage may afford you. The control
is paced through a latch so changes keep time with the incoming external
clock which drives the machine.

The VC input has two modes of operation.  In one, the VC cuts off if the
voltage present is less than .2 volts (below the stage 2 threshold)  With
this arrangement,  you can have an input sitting there that will have no
effect on the counting sequence until that voltage rises to a level above
the .2 volts.  So, if the input was an envelope generator, the sequencer
would be going on it's merry sequential way until you fired the envelope,
then all hell would break loose.

The second mode of ops for the VC inhibits this .2 volt limit, so if the
same envelope generator was connected, the sequencer would sit at stage one
while the eg was inactive until its output told Milton otherwise.  Sounds
wacky?  Not really - this input is scaled to 1v/oct.  If you connect a
keyboard into the input, you now have a 16 stage programmer which advances
one step with each key of the keyboard and will sit at that stage until
another key is depressed (operationally simular to the Buchla Touch Plates
and Serge Programmer).

There is no internal clock on Milton.  It (he) depends on an external
trigger.  That trigger is routed through a flip-flop, allowing both full
manual (buttons) and VC (trigger inputs)  control of start and stop modes,
with leds indicating the state.  there is also a seperate output for that
obedient trigger to the outside world.

There are also two programmable pulse busses. Each stage has a three
position switch which allows the operator to throw a pulse when that stage
is active into one of two separate pulse busses, each have it's own summed
output.  You cannot send a pulse into both busses on the same step.  It
could easily be modified to do this however with an addition switch
intstalled onthe faceplate.  There is as well a master disable (button and
voltage input) to turn off the pulses at these busses at any time you wish.
The pulses at these busses are shaped so two consectutive enabled stages
will in fact give you two pulses - it won't glop them together as one legato
event.

Apart from that, each stage has it's own voltage pot of course, it's own
trigger output jack and it's own led.

There is also a master hold and reset input jacks on Milty as well.

Getting back to the number of possible banks: This system consists
essentially of two boards.  One holds the counting engine and VC controls,
and another holds the pots, the leds, the pulses busses, the summers, the
trigger output jacks.  The counting engine PCBA is terminated with a 16 pin
dip socket, which drives the sequential information through a bank of 4050
line drivers.  Each 'bank board' has an I/O for this buss. Multiple bank
boards can be daisy chained together for a maximum of about 15 simultanious
banks (if my math serves correct).  It may be slightly less than that based
on loading, but it's something obnoxiously large.

Why am I telling you this detail?  I will be producing bare boards of this
beast which may be offered for sale at a reasonable price.  The counting
engine consists of 14 ICs, nine trannies and the associated support
componentry for these.  A fully equipped bank board  (one having the leds,
pulse busses and summers installed) have 5 ICs, two trannies, 32 diodes and
of course 16 pots.  Remember though that not all bank boards will require
the leds and pulse out jacks.  The pots willprobably be on .8 inch centers.

These boards are some time away, but their coming.

I will be posting a quicktime movie of Milton in action in the next week or
so.

best,

Peter